Emerald crab eating coral

Jsusisaliv · Mar 25, 2016

So I bought an emerald crab from my LFS. Asked it it bothered coral. Oh no they said. So I got me one about 2-1/2 weeks ago. I would continue to see him feast on my green star coral. I could never catch him! He did some damage to my green star coral before I could catch him. Every time I would look for him he would be easy to find, he would be tearing into my green star coral! I just grabbed the entire rock out of the tank and FINALLY got him out. He's now happily residing in my refugium where he can eat macro alage until his little hearts desire. So if you love your corals DONT buy an emerald crab!

jrr · Mar 25, 2016

Yeah I've had mixed luck with them. The ones at reef cleaners are guaranteed to eat bubble algae, which I assume is why you got it?

aabjones888 · Mar 25, 2016

I've had a few different ones and some eat coral and some don't. Someone told me that the red eyed ones are bad, but Donno if that's true.

Salty1962 · Mar 25, 2016

Their crabs, if their main food source isn't available, they'll eat the next best thing with algae in them, softies. I had one eat one of my gobies before and it wasn't sick

Jsusisaliv · Mar 25, 2016

No. I got it for the green hair alage which he does eat but seemed to like the coral better. Plus he looked cool. But not cool enough to sacrifice my expensive coral.

jrr · Mar 26, 2016

Hmm, there are much better options for hair algae that aren't as 50/50 on being reef safe. Might want to verify advice from that lfs before any other purchases.

Waters · Mar 26, 2016

I have always had them in my reef tanks without any issues....I guess I have been lucky

jrr · Mar 26, 2016

I've got a couple in mine now, but I've had to take a few out that went rogue.

cwk84 · Jan 8, 2019

Is there any way to get them out without pulling the rocks out? I've tried that but my rocks are too big. I have two that are eating my coral frags. Every frag I put in my nano started being irritated right away and I didn't find out until today that my crabs are eating them. These suckers are so strong I couldn't pull them out.

cmcoker · Jan 8, 2019

cwk84 said:
Is there any way to get them out without pulling the rocks out? I've tried that but my rocks are too big. I have two that are eating my coral frags. Every frag I put in my nano started being irritated right away and I didn't find out until today that my crabs are eating them. These suckers are so strong I couldn't pull them out.

I've led mine away from rock work with nori being held by some tongs. Then let them grab it and pulled them out of the tank.

Reminded me of crawdad fishing in the nearby creek as a kid, except we used bacon..

jd371 · Jan 8, 2019

I added a few recently to take care of some wire algae and so far they are doing a great job. The few times I've seen them on coral I watched them like a hawk but they weren't eating the coral but the surrounding algae. Hopefully none of three go rogue, knock on wood.

NhoJoe · Mar 19, 2021

It happened to me recently where my recently purchased emerald crab nipping on my duncan . I purchased him specifically for bubble algae hoping that it will help me clear it up. BUT never saw it eating bubble algae. Then I saw him on my duncan stalk thinking that he could be eating algae, then one night i saw him eating some kind of bright green stuffs and as I watched closely, it was my duncan, catch him and put him on my HOB refugium. Now my duncan is shrunken with some extended tentacles. Hopefully it recovers from the stress caused by the emerald crab.